Ocular inflammatory diseases, such as macular edema, retinal vein occlusion, and uveitis, can cause blurry vision, double vision, floaters, ocular pain, loss of vision, and may result in blindness.
For treatment, corticosteroids, such as dexamethasone or triamcinolone acetonide (TRIESENCE®), can be injected via intravitreal injection (IVT). Repeated bolus injections of corticosteroids such as TRIESENCE are associated with cataract formation, increased intraocular pressure, vitreous floaters, endophthalmitis, decreased visual acuity, and retinal injury. Patients are administered numerous injections over the course of treatment. This regimen is burdensome for patients and medical care providers.
Intravitreal implants have been developed which deliver a sustained concentration of drug over a period of time. These implants are injected or surgically implanted in the vitreous of the eye for the sustained release of drug to the posterior of the eye. For example, OZURDEX® is an intravitreal implant used for the extended release of dexamethasone to treat various ocular conditions. However, sufficient levels of the drug are released for only approximately 30 to 60 days, and a new implant must be injected into the eye of the patient. Repeated injections may result in pain, headache, conjunctival blood spot, intraocular infection, globe perforation, fibrosis of the extraocular muscles, vitreous detachment, reactions to the delivery vehicle, increased intraocular pressure, and cataract development. Alternatively, an intravitreal implant containing fluocinolone acetonide, ILUVIEN®, has been developed, which releases fluocinolone acetonide over a period of approximately 3 years. This duration of corticosteroid exposure is often too extensive for many patients, and may result in increased risk of corticosteroid-associated adverse effects, including cataract formation and increased intraocular pressure.
Therefore, there is a great need in the medical field for an alternative treatment using a sustained-release delivery system with an improved safety and efficacy profile. An improved sustained release pharmaceutical formulation administered directly to the posterior of an eye would likely improve both compliance and the adverse event profile of current intravitreal implants. Moreover, any extended release implant is highly dependent on the selection of polymers, co-polymers, drug-polymer interaction, load uniformity, porosity, size, surface-area to volume ratio, and the like for providing its drug release and degradation characteristics and the manufacturing techniques used in the prior art implants can induce inherent drawbacks in each of these parameters.